At Cameron Crowe's website, he reprints his 1976 Playboy article and interview with David Bowie (Warning: Discussion includes mature content). Included in the article reprint is this interesting paragraph:

My talks with Bowie began as far back as early 1975. Few of our sessions were marathon affairs. No matter how stimulating the conversation, after any longer than an hour of sitting still, Bowie could barely contain himself. 'Can we just take a short break?' he'd blurt. Not waiting for a reply, he would then shoot to his feet and dart in another direction: sometimes to write a song or two, other times to dash off a painting. In one instance, he ended a session by asking for a random list of 20 items. I gave it to him. He studied the list for ten seconds, handed it back and recited it from memory. Backward and forward.